Process of treating yarn



1943- F. R.' MILLHISER PROCESS OF TREATING YARN Filed Sept. 22, 1944Patented Nov. 9, 1948 UNITED STATES PATENT OFFICE PROCESS OF TREATINGYARN Frederick R. Millhiser, Richmond, Va., assignor to E. I. du Pont deNemours & Company, Wilmington, Del., a corporation of DelawareApplication September 22, 1944, Serial No. 555,210

5 Claims. 1

This invention relates to improving the physical properties of viscoserayon yarn spun to a bobbin by the hot dip process. It relates, moreparticularly, to a process of treating viscose rayon yarn spun to abobbin by the hot dip process to produce a yarn which can be convertedto cord having highly improved resistance to fatigue.

One of the conventional processes for producing viscose rayon yarns, i,e. regenerated cellulose produced from viscose, is the bobbin process.According to such process, a solution of viscose is extruded through asuitable nozzle or spinneret into a coagulatin and regenerating bath,from which the filaments of regenerated cellulose are withdrawn and theyarn filaments leaving the bath are passed to a rotating spool or bobbinon which they are traversed and wound into a cake. Layer upon layer ofyarn is permitted to collect on the bobbin until the accumulated massforms a yarn cake of suitable size for dofiing and subsequent washing,purification or finishing treatment.

Recently there have been developed methods for spinning viscose rayonyarns of high tenacity according to which the coagulating andregenerating filaments are subjected to considerable tension andconsequent stretching between the spinneret and the take-up bobbin andthe yarn is wound on the bobbin under the same high tension at which itwas spun.

United States Patents 1,901,007 and 1,996,989 disclose procedures forproducing viscose rayon yarn of improved tenacity by passin thecoagulated, partly regenerated filaments through a hot aqueous bathheated to 70" C. to 100 C. and, a

while the filaments are in contact with such hot aqueous bath,subjecting them to substantial tension and/or stretching. This procedureis known in the art as the hot dip process.

When the hot dip process was utilized in the bobbin process, there wasproduced a yarn of increased tensile strength. However, the improvementin yarn strength could not be converted to an improvement in tire cordsproduced from such yarn. This was so because such hot dip arn Wasdeficient, principally in transverse strength as reflected in fatigueresistance of cords.

An object of this invention is to produce a rayon yarn which can beconverted to a tire cord having improved physical properties.

Another object of this invention is to provide a rayon yarn which can beconverted to a tire cord having a high resistance to fatigue.

An additional object of this invention is to improve the physicalproperties of a viscose rayon yarn spun to a bobbin by the hot dipprocess.

A further object of this invention is to provide a method of treatingviscose rayon yarn spun to a bobbin by the hot dip process whereby 2 itcan be converted to a cord having a high resistance to fatigue.

Other and additional apparent hereafter.

The above objects are accomplished, in general, by unwinding a viscoserayon yarn, produced by the hot dip process, from the bobbin on which itwas collected at the spinning machine and on which it was washed withwater, and thereafter, while the yarn is still in the gel state,treating it with an aqueous fluid at a temperature above 90 C., the yarnduring such treatment being under a tension of a magnitude not greaterthan 0.02 gram per denier.

The process is preferably carried out on the slasher so that the yarnimmediately after treatment is slashed. In such embodiment of theinvention, after washing the yarn on the bobbin, the bobbins are placedon a creel at the slasher. According to one procedure, a feed rollunwinds the yarn and feeds it onto a traveling belt which conveys theyarn through a steam chamber where it is heated and wetted. Afterleaving the steam chamber, the yarn is passed directly through thefinish bath and into the slasher in the normal manner. The relativerates of speed of the belt and the feed roll are such that the yarnwill, during steaming, be under substantially no ten- S1011.

According to another procedure, the yarn from the creel is fed into asteam chamber in the form of a warp sheet. From the steam chamber, theyarn passes directly through the finish bath and into the slasher in thenormal manner. The steam chamber is located between two pairs of quetchrolls. The relative rates of speed of the quetch rolls are such that theyarn will be under a tension not greater than 0.02 gram per denier.

The nature of the invention will be more clearly apparent by referenceto the following detailed description when taken in connection with theaccompanying drawings in which:

Figure 1 is a diagrammatic perspective view showing one form of anapparatus for carrying out the invention; and

Figure 2 is a perspective view of a modified form of apparatus which canbe used for carrying out the invention.

Fig. 3 is a diagrammatic view of one form of apparatus for washing theyarn on a bobbin.

Referring now to the drawings wherein like reference numerals designatelike parts, the reference numeral Ill designates a plurality of viscoserayon yarns in the gel state being continuobjects will become ouslyunwound from a corresponding number of bobbins 26 by a fluted feedroller 12 driven at a suitable speed by means not shown. The bobbinscontaining the yarn wound thereon at the spinning machine areappropriately mounted on a bobbin creel. The feed roller I2 feedsthe'gel rayon yarns onto a continuous belt conveyer l4 travelin over apair of rollers 16 and it! at the receiving and delivery endsrespectively thereof. The roller H8 at the discharge end is driven. inany suitable manner by means not shown. The surface speed of the feedroller l2 and the surface speed of the belt is are such that the yarns10 are in a relaxed condition on the belt l4 and under substantially notension. Intermediate the delivery and discharge end of the conveyor Hi,there is a steam chamber, generally designated by the reference numeral20, through which the conveyer l4 passes at least during its upperflight. Steam is continuously introduced into the steam chamber throughthe inlet 22, the steam passing from the steam chamber through theoutlet 24. The size of the steam chamber and the rate of travel of theconveyer M are such that, when the yarns on the conveyer pass throughthe steam chamber 20, they will have been subjected to the steamtreatment for the desired period of time. The yarns it, after therelaxing treatment, are passed directly into the slasher in the normalmanner.

In the apparatus shown in Figure 1 and described above, the yarns aresupported on a traveling surface during the relaxing treatment. Theinvention is not restricted to the use of such an apparatus. If desired,the yarns in the form of a warp sheet of threads may be subjected to therelaxing treatment on the run, and an apparatus for carrying out suchprocedure is shown in Figure 2.

Referring now to Figure 2, a plurality of rayon yarns in the gel stateare unwound from a corresponding number of bobbins on which the yarnswere wound at the spinning machine, and constitute a warp sheet ofyarns, which passes through a steam chamber 32 positioned between twopairs of quetoh rolls 3@ and 36. Steam is introduced into the steamchamber 32 through the inlet 38 and passes therefrom through the outlet40. The peripheral speeds of the quetch rolls 34 and 3B are such thatthe warp sheet of yarns is maintained therebetween under a tension, themagnitude of which does not exceed 0.02 gram per denier. The quetchrolls 36 also serve to feed the yarns to the slasher.

The following examples are given to illustrate the specific details ofthe present invention, it being understood that the details as set forthin these examples are not to be considered 1imitative of the invention,and the proportions are by weight:

Example I Cotton linters viscose, containing 7% cellulose and 6% causticand ripened to a salt (sodium chloride) index of 5.2, is extruded into acoagulating and regenerating bath containing 8.0% sulfuric acid, 22.0%sodium sulfate, 0.7% zinc sulfate and 5.0% ferrous sulfate to form ayarn of 1100 denier-480 filaments. The bath is maintained at atemperature of 52 C., the yarn being passed around a plurality of rollerguides so arranged as to provide a bath travel of 130 and impart to theyarn a spinning tension of 0.96 gram per denier. The yarn is then passedthrough a second bath containing water and maintained at a temperatureof from 90 C. to 100 C., constituting the hot dip bath. The yarn isgiven a bath travel of 9" in the hot dip bath and subjected totension soas to stretch the yarn 17%. The yarn is collected on a bobbin at awind-up speed of 3600 per minute and at a wind-up tension of from 100 to1,000 grams. After a cake of app r. u L) priate size has been formed,the spun yarn is washed free of acid and salt while on the bobbin withwater at 55 C. As shown in Figure 3, the yarn l0 may be pressure washedon the perforated bobbin 2G with the washing liquid coming through theconduit 28 to the perforations 30 and then through the yarn. Sufiicientpressure is applied at 32 to seal the bobbin. As shown in Figure 1, thewashed yarn is talren oii the bobbin held on support 3d. The yarn ispassed through a guide 36 and then in the path indicated. The washingstep described may be replaced by any of the other conventional washingprocedures. The yarn from the bobbin is transferred to a tray where in arelaxed state it is wetted out with water and after wetting, whilemaintained under substantially no tension, is subjected to a steamtreatment for about 15 minutes, whereby the temperature of the wet yarnis raised to about 100 C. Thereafter, the yarn is slashed in thewell-known manner.

Example II A plurality of bobbins of hot dip rayon yarn are prepared andwashed free of acid and salts, as described in Example I. The yarn isunwound from the bobbin and treated while in the gel state in theapparatus shown in Figure 1. During treatment, the yarn is undersubstantially no tension.

Example III A plurality of bobbins of hot dip rayon yarn are preparedand washed free of acid and salts, as described in Example I. Aplurality of the gel yarns in the form of a warp sheet are subjected totreatment in the apparatus shown in Figure 2. During treatment, theyarns are under a tension of 0.018 gram per denier or less.

The steam in Examples II and III is wet steam at atmospheric pressure.

Though as shown by the examples, water and steam are preferred, theinvention is notrestricted thereto. In general, any aqueous compositionin which the liquor is predominantly water can be used. Finishingcompositions, dilute caustic or alkali carbonate or alkali bicarbonatesolutions, dilute solutions of wetting agents, dilute solutions ofneutral salts, and cord-dipping solutions are illustrative examples ofvarious aqueous fluids which can be used. Any finishing compositioncontaining 60% to 99% or more of water can be used.

The other ingredients in'the finishing composition may include oils,fats, waxes, wetting agents, anti-oxidants and the like. In the case ofan aqueous solution containing caustic, the

caustic content should be low, for instance, not

more than 1% or 2%. Sodium carbonate or bicarbonate solutions may beused of somewhat higher concentration. Any of the known wetting agentsmay be added to water or to aqueous solutions and generally will be oflow concentration, for instance, less than 3% or 4%. The concentrationof neutral salts in water may vary widely, say from a few percent to 30%or 40%, depending on the solubility of the salt. Likewise, thecord-dipping solution may be of any known nature and concentration solong as it is preponderantly water. The cord-dipping solutions ofTippetts, Serial No. 493,228, issued as U. S. Patent No. 2,419,922, maybe used.

The treatment with the aqueous fluid above C., and particularly steam,afiects primarily the tensile and loop strength Of the yarn as well asthe bone dry strength and fatigue of the cord. In general, the effect isto decrease tensile strength and increase loop strength, at the sametime increasing elongation. The oven dry strength and the conditionedstrength of the cord are increased by the treatment. However, the mostoutstanding effect is on fatigue. regard, the improvement is of theorder of 50% for a yarn spun to the bobbin with low tension and 300% fora yarn spun directly to a bobbin under high tension.

The following tables show the physical properties of cords produced fromviscose rayon yarn spun by the hot dip process and collected on abobbin, which yarn was treated as described in Example I for minutes,and cords produced from viscose rayon yarnspun by the hot dip processand collected on a bobbin and without treatment of the yarn:

AYarn wound to the bobbin at 200 grams tension Treated UntreatedSlashing Conditions:

Stretch, per cent Quetch tension, grams Yarn Properties:

Denier Dry tenacity, g. p. d Wet tenacity, g. p. d Loop tenacity, g. p.d Dry elongation, per cent Wet elongation, per cent Loop elongation, percent Wet contraction, per cent Cord Properties (1100/2 Construction)Conditioned to 12% moisture:

Denier 2 4 Tenacity, g. p. d Elongation, per cent at 10 lb. oadElongation, per cent at break Oven-Dry:

Tenacity, g. p. d Elongation, per cent at 10 lb. load Elongation, percent at break Fatigue rating, per cent Twist:

Single, T. P. I... Ply, T. P. I

B-Yarn wound to the bobbin tension grams Treated Untreated (I -Yarnwound to the bobbin at 1000 tension grams Treated Untreated Loopstrength in grams per denier is the force in grams necessary to breakone or both of two In this.

. properties.

6 v interlocked loops of yarn divided by twice the denier of the yarn.The loop strength is measured in grams on the same type of machine usedfor measuring dry tenacity, the break always occurring at the point ofcontact of the two collapsed, interlocked loops. Resistance to fatigueis measured by the time expressed in hours which a ribbon of cords madeup from a given number of ends of the same type of cord can withstandalternate elongation and relaxation before complete rupture. Theelongation and relaxation of the cord are accomplished by mechanicalmeans under conditions designed to make the test as reproducible aspossible. A conditioned cord is one which has been conditioned for atleast 24 hours to a moisture content of 12%. An oven-dry cord is onewhich has been dried in a drying oven kept at 105 C. In determining thephysicals of an oven-dry cord, the latter is tested immediately uponremoval from the oven and before any substantial regain in moisturetakes place.

Example I sets forth a specific coagulating and regenerating bath in theprocess of producing viscose rayon yarn spun to a bobbin by the hot dipprocess. The invention is, however, not restricted to such specificcoagulating and regenerating baths. A coagulating and regenerating bathwhich contains 11% sulfuric acid, 23% sodium sulfate, 4% glucose and0.85% zinc sulfate may be used. Similarly, the coagulating andregenerating baths disclosed in U. S. Patents 2,347,- 883 and 2,347,884may be used.

The hot dip bath, instead of being water, may be aeidulated water or aviscose regenerating bath of the same or different composition-as thatinto which the viscose is initially spun. Optimum results are obtainedwhen the hot dip bath is maintained at a temperature of about C. to C.,so that stretching will take place in the yarn that is not below 85 C.at the region and time of stretching, although excellent results canoften be obtained at much lower temperatures, such as at 75 C. orthereabouts. The stretch in the hot dip bath may be from 15% to 60%depending on the particular type of spinning arrangement.

In the examples, a specific tension and time of treatment are set forth.In general, the tension of the yarn being subjected to the steamtreatment is of a magnitude which does not exceed 0.02 gram per denier.The time of treatment has generally been of the order of 10 to 15minutes, although it is indicated that the desired result can beobtained by much shorter times of the order of one second if the properhigh temperature is attained in that time.

The invention provides a process for producing viscose rayon yarns ofimproved physical Yarns produced in accordance with this inventionpossess not only a high tenacity and a good elongation, but also animproved and increased loop strength. Cords or plied structures preparedfrom the yarns of this invention have a satisfactory tenacity,elongation, and possess a greatly improved resistance to fatigue. Theseimproved yarns are therefore eminently suited for use in the textilearts, and particularly in the reinforcing of rubber articles such astires.

Since it is obvious that many changes and modifications can be made inthe above-described details without departing from the nature and spiritof the invention, it is to be understood that the invention is not to belimited thereto except as set forth in the appended claims.

i mclaim:

13 A process" for substantially improving" the ""physical properties" ofhot dip multifilament vis- Verted to a tire cordhaving .high'resistanceto atigue,which comprises washing said yarn while o'n the' bobbin,whereby said yarn is washed'acidree' at constant length; unwindingthe'yarmand i treating the unwoundgel yarn with .an aqueous on 'thebobbin whereby said yarn is washedacid fre' at constant length,unwinding' the yarmand steaming the unwound gel-yarn While said gel yarnis under a tension notgr'eaterthan 0.02 gram per denier.

3; Acprocess for substantially improving the physicalprop'erties ofhotdip multifilam'ent viscose' rayon yarn wound up at the "spinning ma- S-Chine on a bobbinwh'ereby the-yarn can be converted to a tirecord-having high resistance to 6 fatigua'which comprises washing saidyarn while" on'the bobbinwhe'reby said yarn is Washed acidfree atconstant length, unwinding the yarn, and treating the unwound gel-yarnwith an aqueous 'fluicl-a't'na temperatureabove 90 C. While said gel=yar"n is under substantially no tension.

4; A process for substantially improving the 1 r physical properties ofhot dip 'multifilament: viscose rayon yarn wound-up atthespinningama--chine on a bobbinwherebythe yarn canJb'e'cQnverted' to a tire cordhavingrhigh resistancev to fatigue, which comprises washing saidyarnwhile on the'bobbinwhereby said yarn is washed'a'cidfree at constantlength, unwinding the yarn; and treating the unwound gel'yarn with wetsteam While said gel yarn is under substantially no tension.

5; A- process for: substantially improving =the physical properties ofhot dip multifilament Niscose rayon yarnwoundup at" thespinningmachineona bobbin whereby the yarn-can'becoin 'verted to a tirecord havingh'igh r'esistanceto fatigue, which comprises washing s'aidyarn while on the bobbin whereby said yarn iswashed' acidfree atconstant length, unwinding a plurality of yarns from a pluralityof'bobbins to form a warp sheet, and treating said warp sheet of gelyarns with wet steam while said gel yarns are under a tension notgreater than 0.02 gram per denier.

FREDERICK R. MILLHISER.

REFERENCES GITED I The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 2,159,097 Moncriefi et a1. May23, 1939 2,298,868 Catlin Oct; 13, 1942 2,340,377 Graumann et a1. Feb.1; 1944 2,346,208 ConaWay. Apr. 11, 1944 2,377,434 Lyem June 5, 19452,388,742

H111 et al. NOV. 13, 1945

